PROGNOSTIC FACTORS IN HEAD INJURY

ANAS HMADE MD

Epidemiology:

Traumatic brain injury is the leading cause of death and disability in adults <44yr and children >1yr.

1500 people per 100.000 population attend emergency every year .

300 admitted for hospital . 15 admitted to neurosurgical department . 9 die

Clinical prognostic indicators

Age : increasing age increases the probability of a poor outcome especially after the age of 60s, children have better outcome .

Hypoxia : when combined with hypotension has positive predictive value of 79% of a poor prognosis .

positive predictive value: the probability that a patient with a positive test result really does have the condition for which the test was conducted.

Blood pressure :

Hypotension at any stage is a strong predictor of outcome. A single hypotensive episode can double the mortality and significantly increase morbidity .

Alone has positive predictive value of 67% of a poor prognosis .

Glasgow coma scale :

Decrease in it increase the probability of poor outcome especially the motor component .

Head Trauma Assessment

Glasgow ScaleEye OpeningMotor ResponseVerbal Response

Head Trauma Assessment

Glasgow Scale--Eye Opening4 = Spontaneous3 = To voice2 = To pain1 = Absent

Head Trauma Assessment

Glasgow Scale--Verbal5 = Oriented4 = Confused3 = Inappropriate words2 = Moaning, Incomprehensible1 = No response

Head Trauma Assessment

Glasgow Scale--Motor6 = Obeys commands5 = Localizes pain4 = Withdraws from pain3 = Decorticate (Flexion)2 = Decerebrate (Extension)1 = Flaccid

Decorticate is toward the Decorticate is toward the corecore((bodybody).).

Decerebrate is away from Decerebrate is away from the bodythe body..

Pathophysiology :Pathophysiology :

If the lesion is above the red nucleus of the midbrain, and thus preserving the rubrospinal tracts(red nucleus preferentially activates the flexors) then you will see decorticate posturing (flexion). If below the red nucleus, then Rubrospinal tracts are gone, and we have unopposed influence from the much lower vestibular nuclei and vestibulospinal tracts (which preferentially activate ipsilateral extensors), causing limb extension, and decerebrate posturing.

GLASGOW COMA SCALE

14 – 15 Mild head injury

13 - 9 Moderate head injury

< 8 Sever head injury

OUTCOME In Severe Brain injury:

Good recovery 25-30% Moderate disability 15-20% Sever disability 15% Vegetative stat 5% Death 30-35%

Pupillary size and responses :

Measured after cardiovascular resuscitation have a significant prognostic weight.

Bilaterally absent pupillary light reflexes have a positive predictive value of >70% of a poor prognosis .

Fixed dilated pupil may result from uncal herniation or brainstem injury with the compression of parasympathetic fibers of the oculomotor nerve

Variables that should be considered include : Correction of hypoxia and hypotension. Exclusion of direct orbital injury. Administration of atropine/anti-cholinergic.

Fixed pupils : response <1mm

Dilated pupils : size >4mm

Asymmetric pupils : differ in size by 1mm or more .

POST TRUMATIC AMNESIA

The duration of post-traumatic amnesia (PTA) is also one of the best predictors of long term outcome following head injury.

Very Mild TBI – PTA of < 5 minutes

Mild TBI – PTA of 5-60 minutes

Moderate TBI – PTA of 1-24 hours

Severe TBI – PTA of 1-7 days

Very Severe TBI – PTA 1-4 weeks

Extremely Severe TBI – PTA > 4 weeks

Lab tests as a predictive values:

Glucose level

Hemoglobin level

Prothrompin time

Platelets count

Radiological Predictive Values

CT scan is the corner stone in radiological assessment in head injury

Done just for hemodynamically stable patient.

Factors associated with worse prognosis :

1. Compressed or absent basal cisterns

2. Traumatic subarachnoid hemorrhage

3. Presence of midline shift

 Marshall CT classification

Grade 1 = normal CT scan (9.6% mortality).

Grade 2 = cisterns present, shift < 5mm (13.5% mortality).

Grade 3 = Cistern compressed/ absent, shift <5mm (34% mortality).

Grade 4 = Shift > 5mm (56.2% mortality(ز

Midline Shift

Midline shift = Biparietal diameter - SP

2

SP= the distance from the inner table to the septum pellucidum on the side of the shift .

The shift is always defined at the level of foramen of monro for standardization.

Obliteration of basal cisterns on CT

Are evaluated at the level midbrain .Divided into :One posterior limb = Quadrigeminal

cistern.And Two lateral limbs = posterior portion

of the ambient cistern .Obliteration of them Caries a threefold

risk of increased intracranial pressure.

Intracranial Pressure:

Elevation correlates with mortality rate following head injury .

Explained by : CPP=MAP – ICP

Genetics and outcome

Patients with apolipoprotein E have more than twice the probability of unfavorable outcome as patients without.

It promotes aggregation of amyloid B-protein into amyloid fibrils.